© 1993 Heron Publishing—Victoria, Canada
A model analysis of the influence of root and foliage allocation on forest production and competition between trees
David A. King
School of Biological Science, University of New South Wales, PO Box 1, Kensington, NSW 2033, Australia / Received August 18, 1992
Summary
A general model was constructed relating forest growth to nitrogen uptake and the partitioning of biomass among leaves, fine
roots and woody tissues. The model was used to assess the influence of the allocation pattern on stand wood production, individual
tree growth and nutrient cycling for even-aged conifer stands with adequate water, but suboptimal nitrogen.
Stand wood production was maximized by quite low allocation to roots for specified amounts of plant-available nitrogen. However,
the wood production of the individual was maximized by higher allocation to roots, because large root systems enhanced the
ability of individuals to compete for nutrients. The optimal fine root allocation for a competing individual was less than
5% of total production for adequate nitrogen, but rose to 30% as nitrogen became more limiting, in general agreement with
observed allocation patterns for fertilized versus non-fertilized forests.
The high allocation to roots predicted for competitors may also enhance long-term productivity by decreasing nutrient losses
from the ecosystem. Although collective, short-term stand wood production could be increased by shifting growth from roots
to stems, this strategy may increase nutrient losses, ultimately decreasing productivity.
Keywords:
forest growth, nitrogen uptake, nutrient cycling, partitioning, stand wood production.
